A dispatch on May 18, 2009 from the US embassy in Beijing quoted a well-placed source saying that Li Changchun ordered the assault on Google after discovering "critical" articles in Chinese about him and his family after Googling his own name.

Mr Li, 66, a member of the politburo standing committee, was ranked as the 19th most powerful person in the world by Forbesmagazine last year, with responsibility for controlling "what 1.3 billion Chinese see, hear and speak". Mr Li was two places lower on the Forbes list than Hillary Clinton, the US secretary of state.

Mr Li and Zhou Yongkang, the head of the public security bureau, allegedly coordinated the attack on Google, which eventually led to the US company closing down its China-based search servers.

The cable was from a trove of 250,000 US diplomatic messages leaked by WikiLeaks, whose contents were dismissed last week by a Chinese foreign ministry official as "absurd."

One Chinese contract also told American diplomats that the campaign against Google was "100 per cent political".

However, it was also suggested that the ultimate goal of the attack had been to steal its source code, essentially the program on which the search engine runs. Armed with the code, China could not only replicate the effectiveness of Google's search engine but also hack into Google at will.

Google admitted, after the attack in December last year that part of its code had indeed been stolen. "They got very close to getting it all," according to one insider.

China's success against Google is also believed to have encouraged the Communist Party to believe it could control the internet effectively.